The role of remnant bone microbiological cultures in managing diabetic foot osteomyelitis

Aim: Effective treatment of diabetic foot osteomyelitis can reduce the risk of major amputations. Our primary aim was to compare the yield in cultures from the proximal and distal segments of bone excised intraoperatively and the impact on antibiotic choice and duration. Methods: Patients with a confirmed diagnosis of osteomyelitis on bone culture results, where both proximal and distal bone segment samples had been collected, were retrospectively reviewed. Microbiological data were examined to identify true pathogens and studied against antimicrobial choice and duration of prescribing. Results: A total of 47 forefoot amputation cases were studied. In 89% of cases, definite or likely pathogens were isolated from the deep tissues cultured. Definite pathogens (Staphylococcus aureus, Group B streptococcus, Group G streptococcus and Streptococcus anginosus) were identified in 32% of cases; in 73% of these, definite pathogens were grown in both the proximal and distal bone segments. Conclusion: Sampling of remnant bone culture can help in reducing the duration of antibiotic treatment in patients (27% of cases in our series) as it is challenging to correctly estimate intraoperatively whether clear surgical margins have been adequately achieved when resecting infected bone.